I have seen this before when internet connectivity isnt there. When IE cant find
www.google.com (due to lack of internet connection), it will start putting www and net etc around what you typed in, thinking that you typed something wrong.
Does this computer have any problems viewing any other sites, or is it just this one?
If it is just this one, clear your temporary internet files (browser cache). After clearing the cache, open a command prompt and type the following:
ipconfig /flushdns
If it is all sites, then you must have a problem with your internet connection.